In many applications it is desirable to provide a high frequency (e.g., greater than 40 GHz) local oscillator (LO) signal, for example, as a clock signal. However, when generating a substantially high frequency LO signal, it is impractical to employ a single LO that directly generates the substantially high LO signal. Therefore, multipliers, dividers, mixers and filters are employed to provide such high frequency LO signals. The multipliers, dividers, mixers and filters upconvert LO signals, downconvert LO signals, mix the upconverted and downconverted signals sand filter out the unwanted components that result from the mixing of the LO signals.
FIG. 1 illustrates an example prior art system 10 for providing a substantially high frequency LO signal. In the example prior art system 10, a 63 GHz LO signal is generated employing a LO 12 that generates an 18 GHz signal. The 18 GHz signal is multiplied three times by a 3-times multiplier 14 to generate a 54 GHz signal. The 18 GHz signal is also divided by two by a divide-by-two divider 16 to generate a 9 GHz signal. The 9 GHZ signal is divided by N by a divide-by-N divider 18 to generate a reference signal, where N is an integer that is greater than one. The reference signal is employed by a phase lock loop (PLL) circuit 20 to correct for errors in the generation of the 18 GHz signal. The 54 GHz signal component is mixed with the 9 GHz signal component via a mixer 22 to produce a 63 GHz signal. The mixing of the two signal components also produces a 45 GHz image signal. Due to the fact that the image signal frequency and the signal frequency are relatively close together (i.e., produce a signal to image frequency of about 1.4), a relatively expensive RF filter 24 needs to be employed for image rejection and to produce an accurate 63 GHz signal.